# Can't get NEW CMP0147 (BuildInParallel) to work

**URL:** https://discourse.cmake.org/t/cant-get-new-cmp0147-buildinparallel-to-work/11478
**Category:** Usage
**Tags:** os:windows, comp:msvc, gen:vs
**Created:** [August 18, 2024, 3:12pm UTC](https://discourse.cmake.org/t/cant-get-new-cmp0147-buildinparallel-to-work/11478 "2024-08-18T15:12:44Z")
**Posts on this page:** 4
**Page:** 1

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### Author: ![JanK](https://discourse.cmake.org/user_avatar/discourse.cmake.org/jank/32/4643_2.png) [@JanK](https://discourse.cmake.org/u/JanK)
#### Post date: [August 18, 2024, 3:12pm UTC](https://discourse.cmake.org/t/cant-get-new-cmp0147-buildinparallel-to-work/11478/1 "2024-08-18T15:12:44Z")

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I’m generating projects for Visual Studio 2022.  
I upgraded my CMake.exe to version 3.30.2.  
Then I bumped my cmake\_minimum\_required to 3.30.  
I also added cmake\_policy(SET CMP0147 NEW) a couple of times into my top-level CMakeLists.txt.

I now expected that the BuildInParallel flag is set to true for all add\_custom\_command calls. However, there is exactly one, which is in the ZERO\_CHECK project. Everything else does not use this flag.

Is there anything else that I’m missing? From the documentation it seems like just setting the policy to NEW should do the trick.

See policy docs here: [https://cmake.org/cmake/help/latest/policy/CMP0147.html#policy:CMP0147](https://cmake.org/cmake/help/latest/policy/CMP0147.html#policy:CMP0147)  
And release notes for 3.27 here: [https://cmake.org/cmake/help/latest/release/3.27.html#other-changes](https://cmake.org/cmake/help/latest/release/3.27.html#other-changes)

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### Author: ![ClausKlein](https://discourse.cmake.org/user_avatar/discourse.cmake.org/clausklein/32/352_2.png) [@ClausKlein](https://discourse.cmake.org/u/ClausKlein)
#### Post date: [August 19, 2024, 5:21am UTC](https://discourse.cmake.org/t/cant-get-new-cmp0147-buildinparallel-to-work/11478/2 "2024-08-19T05:21:44Z")

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Use the `Ninja` generator if you want really parallel builds!

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### Author: ![ben.boeckel](https://discourse.cmake.org/letter_avatar_proxy/v4/letter/b/ea5d25/32.png) [@ben.boeckel](https://discourse.cmake.org/u/ben.boeckel)
#### Post date: [July 21, 2025, 12:00am UTC](https://discourse.cmake.org/t/cant-get-new-cmp0147-buildinparallel-to-work/11478/3 "2025-07-21T00:00:37Z")

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Can you please provide a small test project that shows the problem?

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### Author: ![noahwhygodwhy](https://discourse.cmake.org/user_avatar/discourse.cmake.org/noahwhygodwhy/32/5697_2.png) [@noahwhygodwhy](https://discourse.cmake.org/u/noahwhygodwhy)
#### Post date: [July 29, 2025, 6:48pm UTC](https://discourse.cmake.org/t/cant-get-new-cmp0147-buildinparallel-to-work/11478/4 "2025-07-29T18:48:50Z")

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Hello @ben.boeckel,

Not OP, but I have an example here [GitHub - noahwhygodwhy/BuildInParallelCMakeExample: BuildInParallelCMakeExample](https://github.com/noahwhygodwhy/BuildInParallelCMakeExample)

It doesn’t actually demonstrate the hit to performance due to BuildInParallel that I’m seeing on the full project, but it does demonstrate that the BuildInParallel flag on the custom target RunAllPythonScripts doesn’t get set (which does cause a significant performance gap on the full project)

Project configured and generated using all defaults using cmakegui 4.1.0rc3, targeting visualstudio 17 2022 and msvc.

Please let me know if there’s any other information you need or anything I can help with. Being able to automatically set that setting on cmake generated visual studio projects would be huge for the team i’m on.

Also ninja isn’t currently an option for us currently due to certain factors